DOCSLIB.ORG

An Investigation of Volcanic Depressions Part IV Origin of Hole

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Investigation of Volcanic Depressions Part IV Origin of Hole An Investigation of Volcanic Depressions Part IV Origin of Hole-in-the-Ground, Y a Maar in Central Oregon. (Geological, geophysical, and energy investigations) by Volker Lorenz Center for Volcanology University of Oregon Eugene, Oregon A progress report of work carried out under NASA Research Grant NGR-38-005-012 Alexander R. McBirney, Principal Investigator Table of Contents Abstract. 1 Introduction. • 3 Regional geology 8 Structure. 16 Hydrogeology. 16 Geology of the Hole-in-the-Ground crater 18 Eruption products 25 Ejected blocks 29 Grooved blocks. 33 Muzzle velocities 36 Apparent fluid velocity and density at the orifice*... kO Particle concentration in the eruption cloud at the orifice 45 Eruption pressures 46 Petrographic notes on ejecta types. 48 Frequency distribution of ejecta 53 Shape and depth of the conduit as inferred from ejected blocks. 55 Distribution of ejecta 56 Volume of ejecta above pre-eruption surface 59 Subsurface geology based on evidence from drill-holes 59 Volume of pyroclastic debris below the floor of the crater 71 Geophysical results ?4 Energy requirements 82 Causes of the eruption. 88 Duration of the eruptions . 91 Summary of the history of eruptive activity 93 Comparison with other craters 9^ Comparison of the eruptions at Hole-in-the-Ground with other eruptions. 96 Comparison of the block distribution from the eruptions at Asama, Japan, and Hole-in-the-Ground....... 99 Acknowledgements 102 Selected references 103 Abstract Hole-in-the-Qround is a volcanic explosion crater or maar located in Central Oregon on the edge of Fort Rock basin. At the time the crater was formed between 13*300 and 18,000 years ago a lake occupied most of the basin and the site of the eruption was close to the water level near the shore. The crater is now 112 to 136 m. below the original groundlevel and is surrounded by a rim that rises another 33 to 63 a. higher. The volume of the crater below the original surface is only 60 percent of the volume of the ejecta. The latter contains only 10 percent juvenile basaltic material, mainly sideromelane produced by rapid quench- ing of the lava. Most of the ejected material is fine grained, but some of the blocks of older rocks reach dimensions of 8 m. The largest blocks are concentrated in four horizons and reached distances of 3.7 km. from the center of the crater. Accretionary lapilli, impact sags, and vesicu- lated tuffs are well developed. The crater was formed in a few days or weeks by a series of explo- sions that were triggered when basaltic magma rose along a northwest- trending fissure and came into contact with abundant groundwater at a depth of 300 to 300 m. below the surface. After the initial explosion, repeated slumping and subsidence along a ring-fault led to intermittent closures of the vent, changes in the supply of groundwater, and repeated accumulations of pressure in the pipe. Four major explosive events resulted from pressures of over 300 bars in the orifice of the vent. Ejection velocities during these periods reached 200 meters per second. The corresponding pressures and velocities during intervening, less violent stages were in the range of 200 to 250 bars and about 130 meters per second. The kinetic energy released during the most violent eruptions was po approximately 9 x 10 ergs and the seismic events that must have accom- panied these explosions had a magnitude of about 5» Ejecta 10 centimeters in size were thrown to heights of 2 to 3 kilometers and the eruption cloud may have reached 5 kilometers or more. The axis of eruption was slightly inclined toward the southeast; the form of the vent seems to have had a more important influence than wind. Base surges that accompan- ied some of the explosions left deposits of vesiculated tuff. The total energy derived from the basaltic magma was of the order p, of 5.7 x 10 ergs. Most of this energy went into heating of ground water and the enclosing country rocks; only a small part, possibly a tenth, was released by expansion and vaporization of the water and mechanical processes, such as crushing, acceleration and ejection of debris. Geophysical measurements indicate a domical intrusion below the crater floor and extending upward as a ring dike around the margins of the crater. Introduction Hole-in-the-Ground, a large explosion crater, is situated at the northwestern margin of Fort Rock Basin-Lane County-Central Oregon, approxi- mately 32 km. (20 miles) south of Newberry Caldera (fig. 1). Although not described in geological literature until 1960, this crater has drawn much attention recently because of its resemblance to certain small lunar craters. Owing to their comparable dimensions, Hole-in-the- Ground offers an excellent example that can be compared with Meteor Crater in Arizona. Peterson and Groh (1961) were the first to study the crater. They concluded that it was formed by a single or brief series of violent ex- plosions caused by rising magma coming into contact with water-saturated rocks. More recently (1963) these authors have described similar structures in the vicinity of Hole-in-the-Ground and pointed out a common maar-type origin. • The most recent study undertaken by Kim (1968) centers on gravimetric and geomagnetic measurements and their evaluation. The aim of this study is to give a detailed account of the crater and its genesis and to derive a better understanding of crater-forming processes. Mapping is based on aerial photographs and a topographic map especially compiled from aerial photographs. An important obstacle to detailed geological field investigation is, as Peterson and Groh (1961) have already pointed out, a uniform 60 to 70 cm. thick layer of Mazama pumice that covers most of the area. For this reason, our interpretations are based in large part on results of shallow J§ +it» •rl <M O O I i <oM (0 o rH CO 0) I. 11 0) (0 4> (3 H -rt O 33 0> «> m •H O > rH O Figure 3« View of Hole-in-the-Ground looking east. Fort Rock in the background. Figure 4. View of Hole-in-the-Ground looking northeast. I- X §3 U. ft 8 excavations and drill holes, which together with geophysical data, provide essential information on subsurface structure and rock units. Regional Geology Picture Rock Basalt The stratigraphy of the Fort Rock Basin has been compiled and correlated from scattered outcrops and numerous well logs (Hampton, 1964). The rocks range in age from Pliocene to Recent and consist almost entirely of tuffs, lavas and volcanic sediments. A generalized stratigraphic column is shown in fig. 6. The oldest rocks known in the Fort Rock Basin were described by Hampton (1964) as lava-flows and interbedded tuffs and sediments of the Picture Rock basalt. Lava-flows of this unit are dark grey, blue-grey or dark green, 3 to 16 m. thick and consist of a glassy or microcrystalline groundmass containing olivine-crystals up to 2 mm. and plagioclase crystals up to 6 mm. The interbedded pyroclastic beds and sediments are composed of stratified basaltic tuffs, pumiceous conglomerates and sand- stones. The thickness of this unit may exceed 330 m.; Hampton (1964) tentatively assigns it an age of early Pliocene. The nearest exposures of Picture Rock basalt are 38 km. to southeast of Hole-in-the-Ground at Silver Lake. It is not known whether this unit is present at depth in the Hole-in-the-Ground area. Volcanic rocks of intermediate composition unconformably overlay Picture Rock basalt at Cougar Mountain and Horning Bend (respectively 19 km. southeast and 24 km. east of Hole-in-the-Ground). The volcanic cone at Horning Bend is described by Hampton (1964) as being composed of a fine-grained blue-grey to buff andesite, whereas Cougar Mountain is composed of a glassy to fine-grained rock, probably rhyodacite. The ^^ 6 E E -I I O E 0 O s 10 ro ro ro i^l 2 i ro I ii i o I 10 ° CM O --l-f-.rf _„. , j- I M to •• 10 « I 5 0 s O 0 o o> o 6 ^ E o '-& o *o •o~ 3at O I £o tS: •> 2 • *o 5 C c flB C2D .e. O -.-i.^-1- — r 0 0 3 CD c «o 0 •£ Q. *- 6 O.S g 3 0 o o p •*- o s s X <D > O 0 0. CD I• VO ci 10 maximum thickness of these beds exceeds 330 m. at the central part of both cones, but gradually diminishes laterally. Hampton (1964) estimates their age to be middle Pliocene. 16 km. north of Hole-in-the-Ground intermediate rocks occur at Indian Butte. According to Williams (1957) porphyritic pyroxene andesite and andesitlc basalt flows strike 165-170 southeast and dip both to the west and east. These flows are presumably pre-Pliocene in age. It is not known whether lava-flows at any of these three places reached the area of Hole-in-the-Ground nor whether any vents discharging rocks of similar composition and age occur at depth near Hole-in-the-Ground. The Fort Rock Formation Unconformably overlying the volcanic rocks of intermediate composition and the Picture Rock basalt are, in order of abundance, tuffs, diatomite, basaltic agglomerate and basaltic lava, collectively named the Fort Rock Formation. The tuffs are mainly basaltic lapilli-tuffs and contain inter- bedded diatomite. Near eruptive centers the tuffs become coarse and change finally into basaltic agglomerates. Interbedded basalt-flows are of dark grey color and about 2 to 5 m. thick. On the basis of stratigraphic position, lithology and fossil evidence, the Fort Rock Formation is assigned a middle to late Pliocene age.
Load more

Recommended publications
  • Special Catalogue Milestones of Lunar Mapping and Photography Four Centuries of Selenography on the Occasion of the 50Th Anniversary of Apollo 11 Moon Landing
    Special Catalogue Milestones of Lunar Mapping and Photography Four Centuries of Selenography On the occasion of the 50th anniversary of Apollo 11 moon landing Please note: A specific item in this catalogue may be sold or is on hold if the provided link to our online inventory (by clicking on the blue-highlighted author name) doesn't work! Milestones of Science Books phone +49 (0) 177 – 2 41 0006 www.milestone-books.de [email protected] Member of ILAB and VDA Catalogue 07-2019 Copyright © 2019 Milestones of Science Books. All rights reserved Page 2 of 71 Authors in Chronological Order Author Year No. Author Year No. BIRT, William 1869 7 SCHEINER, Christoph 1614 72 PROCTOR, Richard 1873 66 WILKINS, John 1640 87 NASMYTH, James 1874 58, 59, 60, 61 SCHYRLEUS DE RHEITA, Anton 1645 77 NEISON, Edmund 1876 62, 63 HEVELIUS, Johannes 1647 29 LOHRMANN, Wilhelm 1878 42, 43, 44 RICCIOLI, Giambattista 1651 67 SCHMIDT, Johann 1878 75 GALILEI, Galileo 1653 22 WEINEK, Ladislaus 1885 84 KIRCHER, Athanasius 1660 31 PRINZ, Wilhelm 1894 65 CHERUBIN D'ORLEANS, Capuchin 1671 8 ELGER, Thomas Gwyn 1895 15 EIMMART, Georg Christoph 1696 14 FAUTH, Philipp 1895 17 KEILL, John 1718 30 KRIEGER, Johann 1898 33 BIANCHINI, Francesco 1728 6 LOEWY, Maurice 1899 39, 40 DOPPELMAYR, Johann Gabriel 1730 11 FRANZ, Julius Heinrich 1901 21 MAUPERTUIS, Pierre Louis 1741 50 PICKERING, William 1904 64 WOLFF, Christian von 1747 88 FAUTH, Philipp 1907 18 CLAIRAUT, Alexis-Claude 1765 9 GOODACRE, Walter 1910 23 MAYER, Johann Tobias 1770 51 KRIEGER, Johann 1912 34 SAVOY, Gaspare 1770 71 LE MORVAN, Charles 1914 37 EULER, Leonhard 1772 16 WEGENER, Alfred 1921 83 MAYER, Johann Tobias 1775 52 GOODACRE, Walter 1931 24 SCHRÖTER, Johann Hieronymus 1791 76 FAUTH, Philipp 1932 19 GRUITHUISEN, Franz von Paula 1825 25 WILKINS, Hugh Percy 1937 86 LOHRMANN, Wilhelm Gotthelf 1824 41 USSR ACADEMY 1959 1 BEER, Wilhelm 1834 4 ARTHUR, David 1960 3 BEER, Wilhelm 1837 5 HACKMAN, Robert 1960 27 MÄDLER, Johann Heinrich 1837 49 KUIPER Gerard P.
    [Show full text]
  • A Ballistics Analysis of the Deep Impact Ejecta Plume: Determining Comet Tempel 1’S Gravity, Mass, and Density
    Icarus 190 (2007) 357–390 www.elsevier.com/locate/icarus A ballistics analysis of the Deep Impact ejecta plume: Determining Comet Tempel 1’s gravity, mass, and density James E. Richardson a,∗,H.JayMeloshb, Carey M. Lisse c, Brian Carcich d a Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA b Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USA c Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA d Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA Received 31 March 2006; revised 8 August 2007 Available online 15 August 2007 Abstract − In July of 2005, the Deep Impact mission collided a 366 kg impactor with the nucleus of Comet 9P/Tempel 1, at a closing speed of 10.2 km s 1. In this work, we develop a first-order, three-dimensional, forward model of the ejecta plume behavior resulting from this cratering event, and then adjust the model parameters to match the flyby-spacecraft observations of the actual ejecta plume, image by image. This modeling exercise indicates Deep Impact to have been a reasonably “well-behaved” oblique impact, in which the impactor–spacecraft apparently struck a small, westward-facing slope of roughly 1/3–1/2 the size of the final crater produced (determined from initial ejecta plume geometry), and possessing an effective strength of not more than Y¯ = 1–10 kPa. The resulting ejecta plume followed well-established scaling relationships for cratering in a medium-to-high porosity target, consistent with a transient crater of not more than 85–140 m diameter, formed in not more than 250–550 s, for the case of Y¯ = 0 Pa (gravity-dominated cratering); and not less than 22–26 m diameter, formed in not less than 1–3 s, for the case of Y¯ = 10 kPa (strength-dominated cratering).
    [Show full text]
  • October 2006
    OCTOBER 2 0 0 6 �������������� http://www.universetoday.com �������������� TAMMY PLOTNER WITH JEFF BARBOUR 283 SUNDAY, OCTOBER 1 In 1897, the world’s largest refractor (40”) debuted at the University of Chica- go’s Yerkes Observatory. Also today in 1958, NASA was established by an act of Congress. More? In 1962, the 300-foot radio telescope of the National Ra- dio Astronomy Observatory (NRAO) went live at Green Bank, West Virginia. It held place as the world’s second largest radio scope until it collapsed in 1988. Tonight let’s visit with an old lunar favorite. Easily seen in binoculars, the hexagonal walled plain of Albategnius ap- pears near the terminator about one-third the way north of the south limb. Look north of Albategnius for even larger and more ancient Hipparchus giving an almost “figure 8” view in binoculars. Between Hipparchus and Albategnius to the east are mid-sized craters Halley and Hind. Note the curious ALBATEGNIUS AND HIPPARCHUS ON THE relationship between impact crater Klein on Albategnius’ southwestern wall and TERMINATOR CREDIT: ROGER WARNER that of crater Horrocks on the northeastern wall of Hipparchus. Now let’s power up and “crater hop”... Just northwest of Hipparchus’ wall are the beginnings of the Sinus Medii area. Look for the deep imprint of Seeliger - named for a Dutch astronomer. Due north of Hipparchus is Rhaeticus, and here’s where things really get interesting. If the terminator has progressed far enough, you might spot tiny Blagg and Bruce to its west, the rough location of the Surveyor 4 and Surveyor 6 landing area.
    [Show full text]
  • Insights from Forested Catchments in South-Central Chile
    Institute for Earth and Environmental Science Hydrological and erosion responses to man-made and natural disturbances – Insights from forested catchments in South-central Chile Dissertation submitted to the Faculty of Mathematics and Natural Sciences at the University of Potsdam, Germany for the degree of Doctor of Natural Sciences (Dr. rer. nat.) in Geoecology Christian Heinrich Mohr Potsdam, September 2013 This work is licensed under a Creative Commons License: Attribution - Noncommercial - Share Alike 3.0 Germany To view a copy of this license visit http://creativecommons.org/licenses/by-nc-sa/3.0/de/ Published online at the Institutional Repository of the University of Potsdam: URL http://opus.kobv.de/ubp/volltexte/2014/7014/ URN urn:nbn:de:kobv:517-opus-70146 http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70146 View from Nahuelbuta National park across the central inner valley towards the Sierra Velluda, close to the study area, Biobío region, Chile. Quien no conoce el bosque chileno, no conoce este planeta... Pablo Neruda The climate is moderate and delightful and if the country were to be cleared of forest, the warmth of ground would dissipate the moisture… The Scot Lord Thomas Cochrane commanding the Chilean navy in a letter to the Chilean independence leader Bernardo O’Higgins about the south of Chile, 1890, cited in [Bathurst, 2013] Preface When I started my PhD studies, my main intention was to contribute new knowledge about the impact of forest management practices on runoff and erosion processes. To this end, together with our Chilean colleagues, we established a network of forested catchments on the eastern slopes of the Chilean Coastal Range with water and sediment monitoring devices to quantify water and sediment fluxes associated with different forest management practices.
    [Show full text]
  • View Responses of Scouts, Scout Leaders, and Scientists Who Were Scouts
    ABSTRACT This study of science education in the Boy Scouts of America focused on males with Boy Scout experience. The mixed-methods study topics included: merit badge standards compared with National Science Education Standards, Scout responses to open-ended survey questions, the learning styles of Scouts, a quantitative assessment of science content knowledge acquisition using the Geology merit badge, and a qualitative analysis of interview responses of Scouts, Scout leaders, and scientists who were Scouts. The merit badge requirements of the 121 current merit badges were mapped onto the National Science Education Standards: 103 badges (85.12%) had at least one requirement meeting the National Science Education Standards. In 2007, Scouts earned 1,628,500 merit badges with at least one science requirement, including 72,279 Environmental Science merit badges. ―Camping‖ was the ―favorite thing about Scouts‖ for 54.4% of the boys who completed the survey. When combined with other outdoor activities, what 72.5% of the boys liked best about Boy Scouts involved outdoor activity. The learning styles of Scouts tend to include tactile and/or visual elements. Scouts were more global and integrated than analytical in their thinking patterns; they also had a significant intake element in their learning style. ii Earning a Geology merit badge at any location resulted in a significant gain of content knowledge; the combined treatment groups for all location types had a 9.13% gain in content knowledge. The amount of content knowledge acquired through the merit badge program varied with location; boys earning the Geology merit badge at summer camp or working as a troop with a merit badge counselor tended to acquire more geology content knowledge than boys earning the merit badge at a one-day event.
    [Show full text]
  • Milebymile.Com Personal Road Trip Guide Oregon United States Highway #97 "Dalles California Highway"
    MileByMile.com Personal Road Trip Guide Oregon United States Highway #97 "Dalles California Highway" Miles ITEM SUMMARY 0.0 Welcome to Oregon. California/Oregon State Line - South to city of Weed, California. For highway travel south via California U.S. Highway # 97 See Milebymile.com - Road Map Highway Travel Guide - City of Weed to Oregon/California State Line, for driving directions. Altitude: 4186 feet 0.2 Point of Interest - Photo This highway is called The Volcanic Legacy-Oregon Scenic Byway. Volcanic Legacy-Oregon See attached link for highway driving directions. Altitude: 4180 feet Scenic Byway Highway Sign 0.6 Photo View from highway driving North. Altitude: 4094 feet 2.5 Junction to Keno, OR Keno Worden Road. Northwest to Keno, OR. Altitude: 4121 feet 2.8 Worden Grain Silo Extends over highway to access rail line. Altitude: 4117 feet 3.2 Services at highway Fuel, diesel. Altitude: 4111 feet 4.2 Photo View from highway. Altitude: 4104 feet 9.2 State Rest Area & Info With Oregon travel information center - East side of Oregon highway. Center Paved car parking and trucker/RV parking lot. Altitude: 4098 feet 9.3 Community of Midland, Klamath County's visitor center. Altitude: 4094 feet Oregon 10.3 Access to lodging East side of highway. Altitude: 4094 feet 11.1 Services at highway Fuel, diesel. Altitude: 4094 feet 13.0 Klamath River Crossing the Klamath River, Oregon. Whitewater rafting and kayaking are popular along the upper Klamath River below the J.C. Boyle Dam. Recreational gold panning is popular along the Klamath River. Altitude: 4091 feet 14.2 Junction of Highway #66 West via Highway #66 to community of Keno, Oregon.
    [Show full text]
  • Region Forest Roadless Name GIS Acres 1 Beaverhead-Deerlodge
    These acres were calculated from GIS data Available on the Forest Service Roadless website for the 2001 Roadless EIS. The data was downloaded on 8/24/2011 by Suzanne Johnson WO Minerals & Geology‐ GIS/Database Specialist. It was discovered that the Santa Fe NF in NM has errors. This spreadsheet holds the corrected data from the Santa Fe NF. The GIS data was downloaded from the eGIS data center SDE instance on 8/25/2011 Region Forest Roadless Name GIS Acres 1 Beaverhead‐Deerlodge Anderson Mountain 31,500.98 1 Beaverhead‐Deerlodge Basin Creek 9,499.51 1 Beaverhead‐Deerlodge Bear Creek 8,122.88 1 Beaverhead‐Deerlodge Beaver Lake 11,862.81 1 Beaverhead‐Deerlodge Big Horn Mountain 50,845.85 1 Beaverhead‐Deerlodge Black Butte 39,160.06 1 Beaverhead‐Deerlodge Call Mountain 8,795.54 1 Beaverhead‐Deerlodge Cattle Gulch 19,390.45 1 Beaverhead‐Deerlodge Cherry Lakes 19,945.49 1 Beaverhead‐Deerlodge Dixon Mountain 3,674.46 1 Beaverhead‐Deerlodge East Pioneer 145,082.05 1 Beaverhead‐Deerlodge Electric Peak 17,997.26 1 Beaverhead‐Deerlodge Emerine 14,282.26 1 Beaverhead‐Deerlodge Fleecer 31,585.50 1 Beaverhead‐Deerlodge Flint Range / Dolus Lakes 59,213.30 1 Beaverhead‐Deerlodge Four Eyes Canyon 7,029.38 1 Beaverhead‐Deerlodge Fred Burr 5,814.01 1 Beaverhead‐Deerlodge Freezeout Mountain 97,304.68 1 Beaverhead‐Deerlodge Garfield Mountain 41,891.22 1 Beaverhead‐Deerlodge Goat Mountain 9,347.87 1 Beaverhead‐Deerlodge Granulated Mountain 14,950.11 1 Beaverhead‐Deerlodge Highlands 20,043.87 1 Beaverhead‐Deerlodge Italian Peak 90,401.31 1 Beaverhead‐Deerlodge Lone Butte 13,725.16 1 Beaverhead‐Deerlodge Mckenzie Canyon 33,350.48 1 Beaverhead‐Deerlodge Middle Mtn.
    [Show full text]
  • Lunar Distances Final
    A (NOT SO) BRIEF HISTORY OF LUNAR DISTANCES: LUNAR LONGITUDE DETERMINATION AT SEA BEFORE THE CHRONOMETER Richard de Grijs Department of Physics and Astronomy, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia Email: [email protected] Abstract: Longitude determination at sea gained increasing commercial importance in the late Middle Ages, spawned by a commensurate increase in long-distance merchant shipping activity. Prior to the successful development of an accurate marine timepiece in the late-eighteenth century, marine navigators relied predominantly on the Moon for their time and longitude determinations. Lunar eclipses had been used for relative position determinations since Antiquity, but their rare occurrences precludes their routine use as reliable way markers. Measuring lunar distances, using the projected positions on the sky of the Moon and bright reference objects—the Sun or one or more bright stars—became the method of choice. It gained in profile and importance through the British Board of Longitude’s endorsement in 1765 of the establishment of a Nautical Almanac. Numerous ‘projectors’ jumped onto the bandwagon, leading to a proliferation of lunar ephemeris tables. Chronometers became both more affordable and more commonplace by the mid-nineteenth century, signaling the beginning of the end for the lunar distance method as a means to determine one’s longitude at sea. Keywords: lunar eclipses, lunar distance method, longitude determination, almanacs, ephemeris tables 1 THE MOON AS A RELIABLE GUIDE FOR NAVIGATION As European nations increasingly ventured beyond their home waters from the late Middle Ages onwards, developing the means to determine one’s position at sea, out of view of familiar shorelines, became an increasingly pressing problem.
    [Show full text]
  • GSA TODAY North-Central, P
    Vol. 9, No. 10 October 1999 INSIDE • 1999 Honorary Fellows, p. 16 • Awards Nominations, p. 18, 20 • 2000 Section Meetings GSA TODAY North-Central, p. 27 A Publication of the Geological Society of America Rocky Mountain, p. 28 Cordilleran, p. 30 Refining Rodinia: Geologic Evidence for the Australia–Western U.S. connection in the Proterozoic Karl E. Karlstrom, [email protected], Stephen S. Harlan*, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131 Michael L. Williams, Department of Geosciences, University of Massachusetts, Amherst, MA, 01003-5820, [email protected] James McLelland, Department of Geology, Colgate University, Hamilton, NY 13346, [email protected] John W. Geissman, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, [email protected] Karl-Inge Åhäll, Earth Sciences Centre, Göteborg University, Box 460, SE-405 30 Göteborg, Sweden, [email protected] ABSTRACT BALTICA Prior to the Grenvillian continent- continent collision at about 1.0 Ga, the southern margin of Laurentia was a long-lived convergent margin that SWEAT TRANSSCANDINAVIAN extended from Greenland to southern W. GOTHIAM California. The truncation of these 1.8–1.0 Ga orogenic belts in southwest- ern and northeastern Laurentia suggests KETILIDEAN that they once extended farther. We propose that Australia contains the con- tinuation of these belts to the southwest LABRADORIAN and that Baltica was the continuation to the northeast. The combined orogenic LAURENTIA system was comparable in
    [Show full text]
  • The Physics of Wind-Blown Sand and Dust
    The physics of wind-blown sand and dust Jasper F. Kok1, Eric J. R. Parteli2,3, Timothy I. Michaels4, and Diana Bou Karam5 1Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA 2Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil 3Institute for Multiscale Simulation, Universität Erlangen-Nürnberg, Erlangen, Germany 4Southwest Research Institute, Boulder, CO USA 5LATMOS, IPSL, Université Pierre et Marie Curie, CNRS, Paris, France Email: [email protected] Abstract. The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small- scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan. PACS: 47.55.Kf, 92.60.Mt, 92.40.Gc, 45.70.Qj, 45.70.Mg, 45.70.-n, 96.30.Gc, 96.30.Ea, 96.30.nd Journal Reference: Kok J F, Parteli E J R, Michaels T I and Bou Karam D 2012 The physics of wind- blown sand and dust Rep. Prog. Phys. 75 106901. 1 Table of Contents 1. Introduction .......................................................................................................................................................... 4 1.1 Modes of wind-blown particle transport ...................................................................................................... 4 1.2 Importance of wind-blown sand and dust to the Earth and planetary sciences ...........................................
    [Show full text]
  • Iam Delighted to Present the Annual Report Of
    From the Director’s Desk am delighted to present the Annual Report of the &Communications were planned. One may recall that Indian Statistical Institute for the year 2018-19. This on June 29, 2017, the then Hon’ble President of India, I Institute that started its journey in December 1931 in Shri Pranab Mukherjee, had inaugurated the 125th Birth Kolkata has today grown into a unique institution of higher Anniversary Celebrations of Mahalanobis. learning spread over several cities of India. The Institute, founded by the visionary PC Mahalanobis, continues It is always a delight to inform that once again the its glorious tradition of disseminating knowledge in Institute faculty members have been recognized both Statistics, Mathematics, Computer Science, Quantitative nationally and internationally with a large number of Economics and related subjects. The year 2018-19 saw honors and awards. I mention some of these here. In the formation of the new Council of the Institute. I am 2018, Arunava Sen was conferred the TWAS-Siwei Cheng delighted to welcome Shri Bibek Debroy as the President Prize in Economics and Sanghamitra Bandyopadhyay of the Institute. It is also a privilege that Professor was conferred the TWAS Prize Engineering Sciences in Goverdhan Mehta continues to guide the Institute as the Trieste, Italy. Arup Bose was selected as J.C. Bose Fellow Chairman of the Council. for 2019-2023 after having completed one term of this fellowship from 2014 to 2018. Nikhil Ranjan Pal was The Institute conducted its 53rd Convocation in January appointed President, IEEE Computational Intelligence 2019. The Institute was happy to have Lord Meghnad Society.
    [Show full text]
  • ROLE-IN-THE-GROUND Lake County, Oregon Vol
    ROLE-IN-THE-GROUND Lake County, Oregon Vol. 23, No. 10 THE ORE.-BIN 95 October 1961 STA TE OF OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES Head Office: 1069 State Office Bldg., Portland l, Oregon Telephone: CApitol 6-2161, Ext. 488 Field Offices 2033 First Street 239 S. E. 11 H 11 Street Baker Grants Pass * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * HOLE-IN-THE-GROUND, CENTRAL OREGON Meteorite Crater or Volcanic Explosion? by Norman V. Peterson* and Edward A. Groh** Lewis McArthur, in Oregon Geographic Names, has described Hole-in-the-Ground as follows: "Hole­ in-the-Ground, Lake County. This very remarkable place is well described by its name. It covers an area of about a quarter of a square mile, and its floor is over 300 feet below the surrounding land level. It is about eight miles northwest of Fort Rock." Hole-in-the-Ground is a large, almost circular, bowl-shaped crater in the northwest corner of Lake County. It has a slightly elevated rim and looks very much like the famous Meteorite ·Crater in north-central Arizona. This remarkable resemblance and the lack of an explanation of the origin in the published litera­ ture was brought to the attention of the department by Groh and is the basis for the present study. The original plans for the study included only Hole-in-the-Ground and the nearby larger, shallower crater, Big Hole, but very soon after arriving in the area the writers noticed other interesting volcanic features of explosion origin. These features, shown on the index map (figure 1), include Fort Rock, Moffit Butte, Mop Area / ...• ' *Field geologist, State of Oregon Department of Geology ond Mineral Industries.
    [Show full text]